In simultaneous polishing of both surfaces of a wafer such as double-side polishing, the wafer is held with a carrier for use in a double-side polishing apparatus.
FIG. 8 is a schematic diagram for explanation of wafer double-side polishing with a common double-side polishing apparatus conventionally used. As shown in FIG. 8, the carrier 102 of the double-side polishing apparatus 101 has a holding hole 104 for holding a wafer W. The carrier 102 is formed with a thickness thinner than that of the wafer W.
The wafer W is inserted and held in the holding hole 104. The upper and lower surfaces of the wafer W are interposed between polishing pads 107, which are disposed on the opposing sides of an upper turn table 105 and a lower turn table 106.
The carrier 102 is engaged with a sun gear 108 and an internal gear 109 and thereby rotated and revolved by the rotation of the sun gear 108. The upper turn table 105 and the lower turn table 106 are rotated in opposite directions while a polishing agent is supplied to polishing surfaces such that both surfaces of the wafer W are simultaneously polished by the polishing pads 107 attached to the upper and lower turn tables 105, 106.
The carrier 102 of this type, used in double-side polishing of the wafer W, is usually made of metal. Accordingly, a resin insert 103 to protect a peripheral portion of the wafer W from damage due to the metal carrier 102 is mounted along the internal circumference of the holding hole 104 of the carrier 102 (See Patent Document 1, for example).